Unmanned autonomous vehicles (UAVs), helicopters, and other propeller-driven vehicles take advantage of rotating propeller blades to provide thrust and/or lift for movement. The high rotational speed of the propeller blades typically causes them to emit a characteristic “drone” or whine, which may be displeasing to listeners.
Musical chords include a plurality of tones consisting of one or more intervals. Chords may have pleasing (consonant) or displeasing (dissonant) properties with listeners based on the intervals included within the respective chord. For example, major chords that include a major third and a perfect fifth interval may sound “happy” or “complete.” Conversely, a minor chord that may include a minor third and a perfect fifth may be considered “sad” or “blue.”